SAMPLING PERFORMANCE OF A TOWED MIDWATER GILLNET FOR JAPANESE SARDINESARDINOPS MELANOSTICTUS

Sampling for Japanese sardine Sardinops melanostictus was performed of fshore of Izu-Oshima, Japan in April 1995 to investigate the sampling performance of a towed midwater gillnet on a research vessel. The towe d midwater gillnet (Towed type) and the midwater driftnet (Drift type) of 33, 43 mm mesh size were used. The nets were made of monofilament nylon with twine diameter 0.284 mm. The Drift type was set at the dept h of 30 m, hanging on six buoys with ropes. The depth of the Towed typ e was set in accordance with the depth of sardine shoals located with an echo sounder (50 kHz). The Towed type caught about one hundred sard ines per operation. The length frequencies of sardines caught by both net types were similar. The sampling performance of the Towed type was similar to the Drift type. Additionally, the Towed type was easier to cast than the Drift type, because the net construction of the Towed t ype was simpler. It is considered that the Towed type is efficient gea r for sampling pelagic fishes on research vessels.